1. Field of the Invention
This invention relates to a compact collapsible photographic apparatus, and, more particularly, to a photographic apparatus having electrically operated focusing control by a distance measuring device.
2. Description of the Prior Art
A wide variety of compact collapsible photographic apparatus has been proposed, the most common design of which comprises a front housing having incorporated therein exposure determining means such as shutter means and diaphragm means and a photographic lens optical system and a rear housing having incorporated therein a film cassette chamber and a viewfinder optical system, the front and rear housings being coupled with each other and communicating with each other through a flexible interconnecting means such as a bellows, so that when preparing for photography, the flexible interconnecting means is expanded to create a space between the front and rear housings at a distance suited to perform photography, conversely when it serves no use for photography, the interconnecting means is folded with the front housing being finally positioned extremely close to the rear housing to achieve compactness of the photographic apparatus, as folded, for portable purposes.
In order to form a sharp image of an object to be photographed from a beam of light rays passing through the objective lens system at the exposure plane of a photographic film by moving at least a part of the objective lens system along an optical axis thereof, as the front and rear housings are set in a cooperative position, while allowing for the photographer to look through the finder optical system, it is known to provide an axial position adjusting mechanism for controlling adjustment of that movable part of the objective lens system in axial position relative to the remaining stationary part thereof as operatively connected with an apparatus-to-object distance measuring device, the latter being associated with the finder optical system. This conventional type of photographic apparatus, however, makes use of a mechanical linkage for operative connection between the axial position adjusting mechanism and the distance measuring device, thereby giving rise to a problem that the required structure of the linking mechanism is very complicated.
On the other hand, at the present time, there are available many photographic system of the self-developing type in which a sheet-shape photosensitive material unit having a rupturable pod of developing fluid carried in itself after its exposure is advanced toward the outside of a photographic camera past a development station provided in the camera, so that the developed photograph having a positive image formed on the same photosensitive material surface can be obtained in an instant.
As such sheet-shape photosensitive material or film unit is configured to a larger film format than that of a film adapted for use with an ordinary multi-purpose photographic camera which provides the exposed film of negative latent image which, after being developed, is used to produce a photographic print or prints of enlarged size, it is required that the self-developing photographic camera be provided with an exposure chamber of the larger dimensions compared with the ordinary photographic camera. Thus the bulk of the overall camera structure and the distance between the objective lens and the exposure plane of the film unit become large. What is required for the general photographic camera design is, however, to achieve comfortable handling of the camera for exposure operation and particularly for portability which enables the photographer to find his camera everywhere he goes. In the case of the self-developing cameras, therefore, it is very importance to achieve compactness of the camera structure. It is known to construct such camera from front and rear housings so that they communicate with each other through a flexible interconnecting means such as a bellows so that when this structure is of no use for exposure purposes, the front and rear housings are collapsed to a compact relation with each other by folding the flexible bellows. Conversely when in use, the bellows is expanded to create an exposure chamber between the front and rear housings spaced apart from each other by a distance suited for exposure purposes.
In this type of self-developing camera, when the provision of the aforementioned distance measuring device is made at the rear housing while nevertheless allowing the photographer to adjust the axial position of the movable part of the objective lens by looking through the finder, which is optically isolated from the objective lens, the employment of a mechanical linkage for operative connection between the position adjusting mechanism and the distance measuring device will lead to the difficulties of achieving high accuracy of position control adjustment without unduly large increase in the complexity of the mechanical linkage structure in question and without causing occurrence of mechanical interference between the linking mechanism and an erecting and collapsing mechanism by which the front and rear housings are rendered movable between the operative and inoperative positions this giving a disadvantage of increasing the production cost and the possibility of occurrence of malfunctions.